Researchers reveal permafrost dynamics and climate impacts in Tibetan alpine grasslands

Permafrost and alpine grasslands interact and coevolve, and permafrost temperatures is an important indicator for understanding their interactions and changes.

A research team led by Prof. Wu Qingbai from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences sheds light on the intricate relationship between permafrost temperature, climate change, and alpine grasslands. The study is published in the journal CATENA.

The researchers examined the permafrost under alpine meadows, alpine steppes, alpine desert grasslands, and barren lands to uncover their relationships with climate change and identify the climate factors influencing their changes using time-frequency domain analysis. They observed distinct periodic characteristics in permafrost temperatures in different zones relative to the level of the permafrost table (above, near, and below it).

Temperature dynamics in the active layer above the permafrost table respond primarily to monthly climate variations, while permafrost dynamics below this boundary are influenced primarily by annual climate fluctuations.

In the time domain, the influence of air temperature, precipitation, and wind speed on permafrost dynamics suggests that air temperature has the greatest influence on permafrost temperature at different depths. However, different climatic factors control permafrost temperature at different depths in the time-frequency domain. Especially at deeper levels, it is crucial to consider the effect of wind speed on permafrost.

Among the four alpine grasslands studied, the permafrost beneath alpine meadows emerges as the most sensitive to climate change, showing distinct periodic fluctuations in intensity compared to the other three grassland types.

Finally, the researchers discussed the confirmed protective influence of vegetation on the underlying permafrost. However, more data are needed to fully understand the role of the sand layer.